Okay, so you admit Congress is actively undermining a negotiation without even knowing what they are undermining.And you're right - nobody knows what's in a potential deal, except for the parts leaked by the White House, apparently rejected by Iran, and unacceptable to the 47 in the Senate who are signatories to the letter. Other than that, nobody knows.
The worst part is...sanctions depends on other countries actively supporting the sanctions. The countries that are apart of this negotiation? Yeah, they are the countries that co-operated and made the current sanctions work. If congress ultimately undermines these negotiations the chance are slim they are going to jump back into sanctions.